[engine-failure] PROJ-177-investigating-the-validity-of-the-equipa @ tasks: RuntimeError

Automated report (spec 023 / FR-016) — an unexpected engine failure occurred while processing **PROJ-177-investigating-the-validity-of-the-equipa** at stage `tasks`.

```
RuntimeError: LLMReviewer[constraint_preservation]: review frontmatter has neither `verdict:` nor `concerns:`/`action_items:` — a contentless/truncated review MUST NOT count as acceptance (false-convergence guard). First 200 chars: '```yaml\n---\nreviewer_name: constraint_preservation\nreviewer_kind: llm\nstage: tasks\nartifact_path: projects/PROJ-177-investigating-the-validity-of-the-equipa/specs/001-investigating-the-validity-of-the'
```

The project remains schedulable; it will retry on its normal cadence and recover once the underlying defect is fixed. Closing this issue does not require any project-state change.

Start with the engine path that processes projects/PROJ-177-investigating-the-validity-of-the-equipa/specs/001-investigating-the-validity-of-the... at the tasks stage, then inspect LLMReviewer constraint_preservation handling of review frontmatter. Reproduce spec 023 / FR-016 with the truncated review shown in the report. Done means a contentless review is rejected by the false-convergence guard without causing an unrecoverable engine failure.

Written by the indexing model from the issue text.